The developing unit of an electrostatic image forming apparatus has a toner hopper for storing supply toner. In order to supply toner to the hopper, a toner cartridge is removably coupled with or proximate to the toner hopper. When the supply of toner has become exhausted, the toner cartridge is replaced with a new toner cartridge. Replacement of toner cartridges, frequently conducted in work areas, becomes problematic since the toner is typically supplied as a powder in small particles which can easily soil a person's clothing or hands and the surrounding area, which is undesirable in an office environment. As a result, toner cartridges have been provided with sealing devices to prevent unnecessary or inadvertent scattering of toner.
One example of a sealing device is an elastic sheet which removably covers a toner supplying aperture formed in the bottom of a toner cartridge. The sheet is removed, however, toner attached to the sheet scatters inside and outside of the image forming apparatus. In addition, once the plastic sheet has been removed, it cannot be re-attached to cover the opening if necessary. Thus, if a container is inadvertently opened, it cannot be easily resealed.
Another example of a sealing device provided with a toner cartridge is made by the Nashua Corporation of Nashua, N.H. In the Nashua device, an internal shutter is provided which is integral with the cartridge. A cap disposed over the cartridge has an opening which allows toner to be distributed therethrough or sealed when the internal shutter is disposed over the opening. To prevent distribution of toner through the opening, the operator must carefully align the opening of the cap with the internal shutter of the cartridge. However, sealing devices which rely on the operator to open and close the sealing device can result in mistaken opening of a toner cartridge, or removal of a toner cartridge with an open end, whereby toner powder is inadvertently distributed on the operator and the machine.
Accordingly, what is needed is a toner container assembly which securely and effectively seals the container and can be re-sealed in case of inadvertent opening. What is further needed is a toner container assembly which prevents operator error in opening and closing openings and/or sealing devices of the toner container assembly.